South Korea has vowed to go ahead with artillery drills on a border island shelled by North Korea last month despite Pyongyang’s threat to retaliate again.A South Korea official said on Saturday that the military is ready to respond to any possible provocation. He also said the drills were not expected over the weekend because of bad weather but would be conducted by Tuesday.The one-day, live-fire drills are to be held on Yeonpyeong Island near the tense sea border with North Korea.North Korea has warned that if the South goes ahead anyway, it will strike back even harder than in the November 23 attack that killed four people.Meanwhile, North Korean defectors have launched propaganda flyers into the North from Yeonpyeong Island.They released balloons with 200,000 leaflets, and one thousand US dollar bills. The pamphlets condemned the North’s shelling of the island and the potential succession of Kim Jong-il’s youngest son as leader.North Korea ramped up the tensions on Friday with its warning of retaliation, prompting Russia and China to express concern over tension on the volatile peninsula.In a statement carried by the North Korean official news agency the military said it “will deal the second and third unpredictable self-defensive blow” to protect its territorial waters and that it will be “deadlier than what was made on November 23 in terms of the powerfulness and sphere of the strike”.An earlier statement posted on Pyongyang’s official website Uriminzokkiri warned that another war with South Korea would involve nuclear weapons.The bombardment of Yeonpyeong island last month killed two marines and two civilians. It also injured 18 people and damaged dozens of homes, and came after a firing drill into the sea by South Korean marines based on the island.The South, outraged at the first shelling of civilian areas since the 1950-53 war, has fortified the island with more troops and artillery and vowed to use air power against any future attack.Its military has said artillery will be aimed away from the North as usual during the upcoming drill, but it will respond strongly if provoked.Members of the US-led UN Command are scheduled to observe the drill and about 20 US soldiers will play a supporting role.Meanwhile in Seoul a group of anti-war protesters staged a rally in front of the defence ministry, calling for the military exercise to be stopped.Residents of Yeonpyeong island were also concerned about the live-fire drill, and some of them have gathered on the beach to pray for a peaceful outcome to the current crisis.